IBM OS/390 User Manual
9.4.5.1 TCP/IP Applications using the Sockets API for Assembler
VSE/ESA applications based on the SOCKET Assembler macro cannot be used
on an OS/390 system. They have to be recoded for the OS/390 TCP/IP.
on an OS/390 system. They have to be recoded for the OS/390 TCP/IP.
9.4.5.2 TCP/IP Applications using the Preprocessor API
The HLL preprocessor API which is available on VSE/ESA for PL/I, Assembler
and COBOL is not compatible with the OS/390 TCP/IP interfaces. Therefore,
these programs have to be recoded for the OS/390 system as well.
and COBOL is not compatible with the OS/390 TCP/IP interfaces. Therefore,
these programs have to be recoded for the OS/390 system as well.
9.4.5.3 TCP/IP Applications using the BSD/C Sockets
The BSD (
″
Berkeley
″)
C sockets interface on VSE/ESA is almost compatible to
the C socket API on OS/390. Only some additional (proprietary) functions or
parameters of the BSD/C interface are not supported by TCP/IP on OS/390. This
is why VSE/ESA TCP/IP applications based on the BSD/C sockets usually can be
migrated to OS/390 with only minor code changes.
parameters of the BSD/C interface are not supported by TCP/IP on OS/390. This
is why VSE/ESA TCP/IP applications based on the BSD/C sockets usually can be
migrated to OS/390 with only minor code changes.
9.4.5.4 TCP/IP Applications using the LE/VSE C Socket API
It is highly recommended to use the IBM C for VSE/ESA compiler, the IBM
Language Environment for VSE/ESA (LE/VSE) C run-time environment and the
LE/VSE C socket interface to write TCP/IP applications on VSE/ESA. These are
compatible with the OS/390 X/Open (XPG4.2) compliant socket interfaces. This
assures the maximum in compatibility and portability for cross platform
development. In this case, migrating the applications is just a matter of relinking
them on the OS/390 system. More information about sockets programming can
be found in the
Language Environment for VSE/ESA (LE/VSE) C run-time environment and the
LE/VSE C socket interface to write TCP/IP applications on VSE/ESA. These are
compatible with the OS/390 X/Open (XPG4.2) compliant socket interfaces. This
assures the maximum in compatibility and portability for cross platform
development. In this case, migrating the applications is just a matter of relinking
them on the OS/390 system. More information about sockets programming can
be found in the
TCP/IP for VSE/ESA User
′
s Guide, SC33-6601.
The VSE applications don
′
t have to be necessarily C program since you can use
the LE/VSE C socket API also from within other languages using the ILC
(InterLanguage Communication). This is described in the book
(InterLanguage Communication). This is described in the book
Writing
Interlanguage Communication Applications, SC33-6686.
9.4.5.5 CGI Programs
If you are running VSE/ESA as a Web server and therefore have implemented
CGI (Common Gateway Interface) programs on the VSE system, all these
programs have to be rewritten on OS/390 since the CGI interface on OS/390 is
totally different to the one on VSE/ESA.
CGI (Common Gateway Interface) programs on the VSE system, all these
programs have to be rewritten on OS/390 since the CGI interface on OS/390 is
totally different to the one on VSE/ESA.
9.4.6 Security
Security is an important consideration for an OS/390 system, especially if it
′
s
connected to large TCP/IP networks or even the Internet. TCP/IP on OS/390 has
some built-in internal security mechanism and relies on the services of an
external security manager such as IBM Resource Access Control Facility (RACF).
some built-in internal security mechanism and relies on the services of an
external security manager such as IBM Resource Access Control Facility (RACF).
Basic TCP/IP security definitions on VSE (such as user ID/password) can be
easily defined in RACF for the OS/390 system. If you have implemented your own
security exit on VSE, similar exits can be written for the FTP server function on
OS/390. Furthermore, RACF can be used to protect whole libraries or single
resources from unauthorized TCP/IP access.
easily defined in RACF for the OS/390 system. If you have implemented your own
security exit on VSE, similar exits can be written for the FTP server function on
OS/390. Furthermore, RACF can be used to protect whole libraries or single
resources from unauthorized TCP/IP access.
Additionally, the OS/390 system can be run as a firewall to secure the system
against users coming through the TCP/IP network.
against users coming through the TCP/IP network.
Generally, you can achieve a higher level of security on the OS/390 system
which, of course requires a little more effort to set it up.
which, of course requires a little more effort to set it up.
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VSE to OS/390 Migration Workbook